> > >> So, who makes 256-byte RAM devices at TTL speeds these days. There are all
> > >> sorts of FIFOs of 256 bytes, but I can't find a simple 256-byte RAM any
> > >> more. I also need a 32x8-bit sram, fast (preferably address-access time
> > >> <<10ns) and preferably in a small package.
> > Yes, those parts were OK, except that they are several orders of magnitude
> > too slow. Volatility is not the issue, since it will be changed frequently,
> > but it's VITAL that the parts be quick, i.e. 5-7 ns max, on address access
> > and separate ins and outs would be best. I don't care if I waste 95% of the
> > RAM, but it should have separate ins and outs, and I have seen VERY few of
> > those, particularly in the speed i want.
> Piece from a 16 or 8MB SDRAM rated PC100, thats around 8ns.
Well, AFAIR, these 8ns are only true when reading in page mode,
not for random access.
> Failing that, look into those 8ns, and less 32K x 32bit SRAM chips
> off the super socket 7 boards? SS7 boards runs at 100mhz and some
> have successfully overclocked it over 100mhz.
Also difficult to say, since cache timing is again not that simple.
Especialy since they are synchnonous. And don't forget, they are 3.3V
types, so not exactly TTL.
> or SGRAM which is video ram with seperate dual buses I think in that
> ns speeds you looking for.
That sounds interesting - but again, there are several asumptions about
the access methods to archive this performance.
Basicly I would take something like an AS7C164-8 from Aliance,
which is a standard 8Kx8 SRAM with 8ns Acces Time or only 3ns
OE time. Well, again no independant I/O, which is rather rare
today.
AFAIR there is some 64kx18 SRAM from IBM with seperate data I/O
and a cycl time of some 5ns - but I don't know any distributor.
And it's also only 3.3V (If my personal FlashRAM is still valid).
Also Samsung has a syncronous SRAM with seperate I/O and 7.5ns
access or 10ns cycle - well again no data.
Oh, yes, both are BGA or similar hard to handle packages.
But all asyncronous RAM I can think of has combined I/O :(
--
Der Kopf ist auch nur ein Auswuchs wie der kleine Zeh.
H.Achternbusch
Received on Thu Oct 21 1999 - 08:54:51 BST